BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows the basic layout of a sheet punching and embossing machine in schematic representation.
FIG. 2 shows a punching and embossing station with hydraulically operated movable die in schematic representation.
FIG. 3 shows the individual motion sequences of several punching and embossing stations with hydraulically operated movable dies in schematic representation.
FIG. 4 shows a schematic representation of the control system of the individual motion sequences.
FIG. 5 shows a schematic representation of mechanically operated press drive units.
FIG. 6 shows a schematic representation of the synchronization of mechanically driven press drive units.
FIG. 7 shows a closed feedback control circuit for actuating the mechanically drive press drive units.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
FIG. 1 shows the basic layout of a sheet punching and embossing machine 100 for the punching, breaking-off and stacking of sheets of paper, cardboard, or other stock material. The punching and embossing machine 100 includes, for example, a feeding attachment 1, two punching and/or embossing stations 2, 2′, a breaking-off station 3 and a delivery attachment 4, being supported and enclosed in a common machine housing 5.
The sheets 6 are fed individually from a stack by a feeding attachment 1 and fed via a feed table 16 to the sheet punching and embossing machine 100, grasped by grippers at their front edge and intermittently pulled through the various stations 2, 2′, 3 and 4 of the punching and embossing machine 100 in the sheet delivery direction F. The grippers are fastened to gripping rods, which are fastened to gripping carts 8, which are in turn attached to a transport system 7.
The punching and/or embossing stations 2, 2′ include a lower table 9 and an upper table 10. The lower table 9 is fixedly mounted in the machine frame and provided with a counterplate for punching blades, not shown. The upper table is mounted so as to be vertically movable up and down and provided with punching and grooving blades.
The gripper carts 8 including the grippers transport the sheet 6 (in directions x, x′, x″ shown in FIG. 3) from the punching and embossing stations 2, 2′ to the breakaway station 3, which includes breakaway dies. In the breakaway station 3, the unneeded scraps are pushed downward from the sheet by the breakaway dies, so that the scraps 11 drop into a container cart 12 positioned under the station.
From the breakaway station 3, the sheet is transported to the delivery attachment 4, where the sheet is either stacked or separated into individual copies at the same time. The delivery attachment 4 may also include a pallet 13, on which the individual sheets are stacked to form a pile 14. When the pile reaches a desired height the pallets with the stacked sheets 14 disposed thereon is transported away from the area of the punching and embossing machine 100.
FIG. 2 shows one of the processing stations 2, 2′, for example, a punching or embossing station, of a sheet punching and embossing machine 100 according to preferred embodiments of the present invention. The sheet 6 being processed is transported by the conveying device 7, 8 (8, 8′, 8″ shown in FIG. 3) in the conveying direction F of the sheet into the processing station 2, 2′. The processing stations have a movable upper table 10 and a lower table 9 fixed to the housing. Four hydraulic cylinders 16 for applying a punching force to the punching die are located in the lower portion of the machine. The hydraulic cylinders 16 are connected to the upper table 10 and are mounted in the machine frame of the sheet punching and embossing machine. The hydraulic cylinders 16 produce a punching stroke in the direction Z, by which the upper table 10 is moved against the fixed lower table 9.
FIG. 3 shows the individual motion sequences of several processing stations 2, 2′, 2″ with hydraulically operated movable tables. The upper tables 10, 10′, 10″ are each driven in the directions z, z′, z″ by one or more hydraulic cylinders 16, 16′, 16″ (in the preferred embodiment, two hydraulic cylinders are shown) toward the lower tables 9, 9′, 9″. So as not to include the pressure connection ports on the cylinders, the piston is secured to the moving part (here, the upper table 10, 10′, 10″), and the cylinder is secured to the machine frame. The upper tables 10, 10′, 10″ each describe a motion in the coordinate Z, while the motions z, z′, z″ can be controlled individually from one upper table to another, depending on the job and the specific operation being performed in the processing station.
In FIG. 4, the control system of the individual components is schematically shown. From a setpoint generator 17, which generates the global machine reference angle αREF, referencing the machine clock and the machine positions, a nominal reference value is individually generated:
Z2,REF for the upper table 10 of station 2,
Z2′REF for the upper table 10′ of station 2′,
Z2″,REF for the upper table 10″ of station 2″,
and so forth.
Starting from this central setpoint generator 17, therefore, a reference value or “machine angle” is defined, which provides the input variable for the feedback control of the individual stations, as well as the drive system, which may be defined, for example, by several linear drives. The upper tables are then regulated to the setpoint reference produced in the position feedback control circuit. The controlling of such individual hydrostatic drive units is known and described, for example, in the hydraulics lecture notes: Murrenhoff, H.: Fundamentals of Fluidics, Vol. 1: Hydraulics, 4th ed. 2005; Murrenhoff, H.: Servohydraulics, 2nd ed. 2002.
Instead of a movable upper table 10, 10′, 10″, a movable lower table 9, 9′, 9″ may be used.
Instead of two cylinders 16, one cylinder or more than two cylinders may be used for the drive.
The cylinders 16 may be located at any suitable positions on the upper table 10.
The cylinders may have designs of varying strengths.
The position and pressure of the cylinders may be individually regulated in order to compensate for unevenness of the packaging materials or local material deficiencies.
For the position control, a displacement control system (regulating the flow into the cylinders by a variable displacement pump) or a resistance control (the flow into the cylinders is regulated by valves) may be used.
One alternative is the use of several mechanical press drive units that are synchronized to each other.
FIGS. 5 and 6 show a schematic representation of mechanically operated punching and embossing stations 2 and 2′, each of which includes any arbitrary number of stations disposed upstream in the direction of arrow A or downstream in the direction of arrow B. The punching and embossing stations 2 and 2′, and any stations upstream or downstream from them, include one press drive 19, 19′ for each movable upper table 10, 10′, including, not further illustrated, a disk flywheel coupled and connected to the gearing which moves the upper table 10, 10′ via eccentric shafts 22, 22′. The press drive is driven, for example, across a reduction gearing 20, 20′ from a drive motor 18, 18′. The power flows directly from the disk flywheel to the platen. A small gearing 26, 26′ is provided to synchronize the individual press drives, which does not transmit any major power flow and joins the press drives 19, 19′ to a king shaft 21, e.g., for synchronization.
Alternatively, synchronization may be provided by individual drive motors for the disk flywheels, which are controlled as servo-drives.
FIG. 7 shows the feedback control circuit for actuating the press drives. As shown in FIG. 7, both a rotary speed control and a position control are performed.
The feedback control circuit shown in FIG. 7 is used to adjust the control variable αex to the setpoint αref. The quantity ωref is used here in the form of a setpoint lock-on to avoid position errors. ωref is the first derivative of the setpoint αref with respect to time.
The comparison of αex and αref is performed by a subtraction element. A subsequent proportional element 25 amplifies the control deviation αdiff and adds it as ωref′ to ωref. From this sum, ωex is subtracted to generate a control deviation ωdiff. This control deviation ωdiff is further processed by, for example, a PI-element 23, into a motor torque setpoint Mref in order to avoid permanent control deviations. The transfer functions 27, 28 symbolize the dynamic behavior of a current controller (motor controller) and the mechanical system being governed. The movement condition (αex and ωex) is detected by a position sensor 29. The output of this position sensor is the position value αex. αex is feedback to the subtraction element S1 for the comparison with αref. Moreover, the time derivative of αref is generated in the differentiator 24, so that it can be provided as ωex to the subtraction element S2.
While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.
Patent Application
20080022821
